Crow Richard S, Hannan Peter J, Folsom Aaron R
Division of Epidemiology, University of Minnesota, 1300 South 2nd Street, Suite 300, Minneapolis, Minn 55454, USA.
Circulation. 2003 Oct 21;108(16):1985-9. doi: 10.1161/01.CIR.0000095027.28753.9D. Epub 2003 Sep 29.
Heart rate-corrected QT interval (QTc) is the traditional method of assessing the duration of repolarization. Prolonged heart rate-corrected QT interval is associated with higher risk of mortality in patients with coronary heart disease (CHD) and in the general population. However, the QTc is typically not evaluated when QRS duration is > or =120 ms, because increased QRS duration (QRSd) contributes to QT interval prolongation. In these circumstances, the JT interval has been proposed as a more valid way to assess ventricular repolarization.
To allow for variation in heart rate, corrected JT interval (JTc) was defined as QTc-QRSd. Using data from the Atherosclerosis Risk in Communities Study, JTc and QTc were compared for their prognostic associations with incident CHD events among 14 696 men and women who were CHD-free at baseline, having either normal conduction or wide QRS complex. Among individuals with normal QRS duration, logistic regression adjusted for age, hypertensive status, diabetes, race, systolic blood pressure, smoking, HDL and LDL cholesterol, R-R interval, and menopausal status in women showed QTc and JTc were nonpredictive of future coronary events in men but significant in women. In individuals with wide QRS complex (QRSd > or =120 ms), similar analyses showed JTc had a significant prognostic advantage compared with QTc in men but not in women, among whom only 11 events occurred.
The JTc is a simple measurement that is a significant independent predictor of incident CHD events in men with wide QRS complex.
心率校正QT间期（QTc）是评估复极持续时间的传统方法。心率校正QT间期延长与冠心病（CHD）患者及普通人群的较高死亡风险相关。然而，当QRS波时限≥120 ms时，通常不评估QTc，因为QRS波时限增加（QRSd）会导致QT间期延长。在这种情况下，JT间期被认为是评估心室复极更有效的方法。
为了考虑心率变化，校正JT间期（JTc）定义为QTc - QRSd。利用社区动脉粥样硬化风险研究的数据，在14696名基线时无冠心病、传导正常或QRS波增宽的男性和女性中，比较了JTc和QTc与冠心病事件发生的预后关联。在QRS波时限正常的个体中，经年龄、高血压状态、糖尿病、种族、收缩压、吸烟、高密度脂蛋白和低密度脂蛋白胆固醇、R - R间期以及女性绝经状态校正的逻辑回归分析显示，QTc和JTc对男性未来冠心病事件无预测价值，但对女性有显著意义。在QRS波增宽（QRSd≥120 ms）的个体中，类似分析显示，与QTc相比，JTc在男性中具有显著的预后优势，但在女性中没有，女性中仅发生了11例事件。
JTc是一种简单的测量方法，是QRS波增宽男性冠心病事件发生的显著独立预测因子。
